Mice, drought, or beetles may harm junipers

I have some Tams Junipers about 30 years old that have various branches that die every year. Is this normal and can I do anything about it?

— Paul

There are several possibilities. One of the more unusual causes for this is damage to the plant by mice.

During the winter, when food is a bit scarce, mice will sometimes chew the bark of junipers, killing that particular branch. This damage usually shows up as patches of dead growth in the plant as things start warming up in the spring.

If you trace down from one of these patches, you’ll eventually run into a section of the branch (usually down near the base of the plant) that’s missing bark. I’m not talking about cracking and peeling bark — a mature stem’s bark is naturally that way — but where the bark is missing completely.

Instead of the normal dark brown of the bark, it will be light brown or tan where the inner wood is exposed.

If you run into this, you’ll want to put some mouse traps out or bait such as D-Con to get rid of the rodents.

Another possibility are twig borers. These tiny beetles bore under the bark of the smaller twigs out near the end of the branches. They are active during the spring and summer, and we usually see their damage in the summer or early fall.

Instead of patches of dead growth, you’ll see small individual dead twigs. Unfortunately, identifying these little buggers is difficult without a magnifying lens.

Twig beetles aren’t all that common, but if they are what you have, you’ll need to spray the plant two or three times with a 38 percent Permethrin concentrate, diluted according to label directions.

If you suspect this might be going on, bring a sample in for us to look at or drop it by the CSU Extension Office at the Mesa County Fairgrounds.

The last two possibilities that come to mind are winter drought damage and physical damage. These will look like the twig beetle damage in that you’ll have scattered, individual dead twigs.

Physical injury will be easy to see if you look carefully as the twig will be broken, scraped or just bent. That’s all it takes for damage like this to occur. I usually see physical injury where there’s a possibility of someone or something bruising or crushing some twigs or branches. I’ve seen it with kids, dogs, even deer.

Winter drought isn’t all that common since junipers are pretty tough and hardy, but occasionally it shows up. The damage will usually only manifest itself where the juniper is exposed to mostly sun, the south or west sides. If the die-back is in areas that get shaded, I’d probably look for another cause, but if this makes sense, then simply watering the plant two or three times over the winter should solve the problem.

If none of these possibilities match what you see on your junipers, bring a sample by our nursery for us to look at.

What time of year do you recommend pruning honeysuckle vines to remove old growth?

— Kathy

My first choice would be early in the spring, probably mid- to late March.

It could be done in late spring, but it will delay or even eliminate much of the flowering of the vine.

The advantage to doing it during the growing season is that you easily can tell the that stems are alive and those that are dead, which is harder in March.

I don’t know if that really makes that much difference, but if it was my vine, I’d do it in March.

Dennis Hill is the nursery manager at Bookcliff Gardens, http://www.bookcliffgardens.com. Send questions to Bookcliff Gardens, 755 26 Road, Grand Junction 81506; or email .(JavaScript must be enabled to view this email address).


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